(1) Field of the Invention
The present invention relates to an electroconductive fibrous material. More particularly, the present invention relates to an electroconductive fibrous material which is valuable as an electromagnetic wave shielding material or a parabolic antenna reflecting material in electronic equipments such as wireless installations including television and radio sets and electronic application devices. The present invention also relates to a collapsible parabolic antenna.
(2) Description of the Related Art
With development of electronic equipments and installations, electromagnetic waves have been widely utilized. Accordingly, interference occurs between one electromagnetic wave and another and electromagnetic waves have an adverse influence on one another, and thus various problems arise. As means for avoiding these electromagnetic wave problems, there have been developed various electromagnetic wave shielding materials. For example, metallic wire mesh (knitted metal wire mesh and expanded metals) and electroconductive textile materials obtained by chemically plating a fiber or a fabric or coating a fiber or a fabric with an electroconductive paint, as disclosed in Japanese Unexamined Patent Publication No. 49-29,901.
Since an electroconductive material prepared from a metallic wire mesh or plate-like material as described above has poor bending characteristics, bending or cutting of the material is difficult. Also, the weight of such a material is excessive and the material is not suitable for use when the weight or size of devices or apparatuses must be reduced. Moreover, a metal wire mesh formed of metal yarns having a fine diameter has a disadvantage in that wrinkles are readily formed and shaping is difficult.
L'INDUSTRIE TEXTILE NO. 1133, MAI, 1983 introduced an electroconductive fabric prepared by inserting metal fibers into warps and wefts at the fabric-forming step. In this fabric, however, since metal fibers are linearly inserted as in the case of a woven fabric of a metal, the bending characteristics are poor and the fabric is not suitable for the formation of an article having curved faces.
A material obtained by forming an electroconductive coating layer on a textile fabric by chemical plating or coating is not easily wrinkled and has a relatively light weight, and this material is suitable for use in an apparatus or device for which the weight and size must be reduced. In this material, however, the peel strength of the coating layer and the durability thereof are unsatisfactory. Moreover, large deviations of the quality due to uneven plating or coating occur, and the manufacturing cost is large.
Since the start of particle utilization of broadcasting satellites there have been serious developments in the use of parabolic antennae. Reflecting bodies used for conventional parabolic antennae are generally prepared from draw-formed products of aluminum plate or FRP plate rendered electroconductive by the incorporation of metal wire meshes, aluminum-vacuum-deposited glass fibers or carbon fibers. However, these reflecting bodies have disadvantages in that the processing steps are complicated, the manufacturing cost is large, the resistance to wind is unsatisfactory and fluctuations of the wave reception state by so-called deflections are large. In order to prevent such deflections, it is necessary to increase the weight of the reflecting body, and if this requirement is satisfied, the handling of the antenna becomes difficult and the manufacturing cost is increased. Furthermore, a parabolic antenna formed of a metal plate is heavy and is difficult to carry about, and a large space is necessary for mounting this type of antenna.